Metallocene polyethylene blend compositions

Abstract

PCT No. PCT/JP96/02072 Sec. 371 Date Mar. 24, 1997 Sec. 102(e) Date Mar. 24, 1997 PCT Filed Jul. 24, 1996 PCT Pub. No. WO97/04026 PCT Pub. Date Feb. 6, 1997An ethylene type polymer composition comprising 20 to 90% by weight of an ethylene type polymer (A) and 80 to 10% by weight of an ethylene type polymer (B). The ethylene type polymer (A) is an ethylene polymer or a copolymer of ethylene and an alpha -olefin of 3 to 20 carbon atoms and has a density (dA) of 0.96 to 0.980 g/cm3 and an intrinsic viscosity ( eta ) of 0.5 to 3.0 dl/g. The ethylene type polymer (B) is an ethylene polymer or a copolymer of ethylene and an alpha -olefin of 3 to 20 carbon atoms and has a density (dB) of 0.91 to 0.965 g/cm3 and an intrinsic viscosity ( eta ) of 1.0 to 10 dl/g. At least one of the ethylene type polymers (A) and (B) is an ethylene type polymer prepared by the use of a metallocene catalyst. The ethylene type polymer composition has the properties: dA/dB is larger than 1; the density is 0.940 to 0.970 g/cm3; the MFR is of 0.005 to 20 g/10 min; the MFR and the melt tension (MT) satisfy the relation log(MT)>/=-0.4 log(MFR)+0.7; and the diametrical swell ratio exceeds 1.35. From this composition, molded articles having excellent mechanical strength and rigidity can be obtained.

What is claimed is: 
     
       1. An ethylene polymer composition comprising: (A) a first ethylene polymer in an amount of 20 to 90% by weight, said first ethylene polymer being an ethylene polymer or a copolymer of ethylene and an α-olefin of 3 to 20 carbon atoms and having the following properties: (A-1) the density (d A ) is in the range of 0.96 to 0.98 g/cm 3  ; and   (A-2) the intrinsic viscosity (η), as measured in decalin at 135° C., is in the range of 0.5 to 3.0 dl/g; and     (B) a second ethylene polymer in an amount of 80 to 10% by weight, said second ethylene polymer being an ethylene polymer or a copolymer of ethylene and an α-olefin of 3 to 20 carbon atoms and having the following properties: (B-1) the density (d B ) is in the range of 0.91 to 0.965 g/cm 3 , and   (B-2) the intrinsic viscosity (η), as measured in decalin at 135° C., is in the range of 3.0 to 10 dl/g;     at least one of said first ethylene polymer (A) and said second ethylene polymer (B) being an ethylene polymer prepared by the use of a metallocene catalyst   wherein said ethylene polymer composition has the following properties: (1) a ratio (d A  /d B ) of the density (d A ) of the first ethylene polymer (A) to the density (d B ) of the second ethylene polymer (B) is larger than 1;   (2) the density is in the range of 0.940 to 0.970 g/cm 3  ;   (3) the melt flow rate (MFR, measured at 190° C. under a load of 2.16 kg) is in the range of 0.005 to 20 g/10 min;   (4) the melt flow rate (MFR) and the melt tension (MT) satisfy the following relation   log(MT)≧-0.4 log(MFR)+0.7; and       (5) the diametrical swell ratio exceeds 1.35, wherein the diametrical swell ratio is measured in the following manner: Capillograph--1B (barrel diameter: 10 mm, manufactured by Toyo Seiki Seisakusho) is equipped with a tubular nozzle (inner diameter (D o ): 3 mm, outer diameter: 4 mm, length: 10 mm) and a barrel (to be charged with a sample) is heated to 200° C. and maintained at that temperature; the barrel is charged with 10 g of a sample; then, a piston is fitted, and degassing is performed, followed by preheating for 6 minutes; after the preheating, the sample is extruded at each piston speed of 10, 20, 30, 50 and 75 mm/min; the diameter (D i ) of the strands thus extruded are measured at a position 15 mm downward from the nozzle tip; a ratio (D i  /D o ) of the strand diameter (D i ) measured at each piston speed to the tubular nozzle diameter (D o ) is plotted against the piston speed on semi-logarithmic paper to obtain a curve; from this curve, a ratio corresponding to the piston speed of 50 mm/min is read out, and this value is taken as the diametrical swell ratio.       
     
     
       2. The ethylene polymer composition as claimed in claim 1, wherein the first ethylene polymer (A) and/or the second ethylene polymer (B) is prepared by the use of a carrier supported metallocene catalyst comprising: [I] a transition metal compound represented by the following formula (I): ##STR3##  wherein M is a transition metal atom of Group 4 to Group 6 of the periodic table, R 1 , R 2 , R 3  and R 4  are the same as or different from each other, they are each hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms, a halogenated hydrocarbon group of 1 to 20 carbon atoms, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, or a part of the adjacent groups of R 1  to R 4  are bonded to each other to form at least one ring together with carbon atoms to which they are bonded,   X 1  and X 2  are the same as or different from each other, and are each hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms, a halogenated hydrocarbon group of 1 to 20 carbon atoms, an oxygen-containing group, a sulfur-containing group or a nitrogen-containing group, and   Y is a divalent hydrocarbon group, a divalent silicon-containing group or a divalent germanium-containing group;     [II] a compound which is capable of activating the transition metal compound [I] and is at least one compound selected from: (II-1) an organoaluminum compound,   (II-2) an aluminoxane, and   (II-3) a compound which reacts with the transition metal compound [I] to form an ion pair; and     [III] a particle carrier.